This project aims at strengthening the research on our SCOR program in several areas where past progress has led to the development of extensions to existing projects or to new projects which arose from ongoing SCOR research. The proposed work includes studies on the pathogenesis of bronchial asthma, using airway responses in human subjects as well as determination of cyclic nucleotides and electrophysiological measurements in isolated airway muscle tissue, on diffusing capacity and airway responses in healthy persons, on chemical identification of pharmacological agent causing byssinosis in textile workers, on biochemical defense mechanisms against inhaled pollutants such as ozone and cigarette smoking, and on fetal lung maturation.